On the cosmological evolution of alpha and mu and the dynamics of dark energy

TL;DR

This paper investigates how the cosmological evolution of fundamental constants alpha and mu relates to dark energy dynamics within scalar field models, highlighting the constraints and potential limitations of current observational bounds.

Contribution

It introduces a framework linking scalar field models to variations in alpha and mu, analyzing the impact on dark energy evolution reconstruction.

Findings

Low-redshift constraints strongly limit high-redshift variations.

More general models can relax these constraints.

Reconstruction of dark energy evolution may be compromised.

Abstract

We study the cosmological evolution of the fine structure constant, $\alpha$, and the proton-to-electron mass ratio, $\mu=m_p/m_e$, in the context of a generic class of models where the gauge kinetic function is a linear function of a quintessence-type real scalar field, $\phi$, described by a Lagrangian with a standard kinetic term and a scalar field potential, $V(\phi)$. We further assume that the scalar field potential is a monotonic function of $\phi$ and that the scalar field is always rolling down the potential. We show that, for this class of models, low-redshift constrains on the evolution of $\alpha$ and $\mu$ can provide very stringent limits on the corresponding variations at high-redshift. We also demonstrate that these limits may be relaxed by considering more general models for the dynamics of $\alpha$ and $\mu$. However, in this case, the ability to reconstruct the evolution of the dark energy equation of state using varying couplings could be seriously compromised.